Remarkable reversal of the non-linear effect in the catalytic enantioselective allylic oxidation of cyclohexene using copper proline complexes and t-butyl hydroperoxide

Abstract

Several examples of efficient catalytic conversions of cyclohexene to optically active 2-cyclohexenyl propionate are reported using t-butyl hydroperoxide as oxidant. With the bis (S)-prolinato copper(II) complex enantioselectivities up to 63% with good conversions were obtained. A negative non-linear ligand effect was observed. Addition of catalytic amounts of anthraquinone resulted in a higher enantioselectivity as well as a reversal of the non-linear effect. Copyright (C) 1996 Elsevier Science Ltd